I cannot get my pavillion 6430 to run after

Hello,
I have not been able to get my hp (Vista) to run after my niece asked to charge her mp3 player on it. The mp3 device was plugged and I left, returning several hours later to find my computer off. I thought she had turned it off. I turned on my computer and up popped a screen saying USB overload and computer will shut down in 10 seconds. It did that a couple of times when I tried to turned it on. So I was not sure what to do and tried to hit escape, which then brought up a blue hp screen. It has 4 options listed: none of them work. So I tried turning on the computer and hitting f8 repeatedly as soon as I turn it on. Nothing happens and if I try Esc=boot menu, it says that it is loading but never does. It also does the same with f10=setup. Nothing happens.
I was told to remove and reseat the ram cards but that did nothing at all. I am not that computer savy but I really appreciate any help.